The Study On Architecture Analysis And Remaining Oil Distribution Patterns Of Beach-bar Reservoir

Most of the fields that were put into development in the 1980s and 1990s in China(including the Wanglongzhuang Oilfield)have entered the stage of high-water or extra-high water-containing oil recovery,but the recovery rate is generally only about 30%,and there are considerable anounts of residual oil distributed in different forms of reservoirs with low water-flooding efficiency.Since the flow of underground fluids is controlled by the size,shape,and spatial distribution of reservoir sandbodies.Therefore,it is extremely urgent to study the architectural of reservoirs in underground beach-bars and the model of residual oil distribution.Taking the second section of Funing formation in the Wanglongzhuang Oilfield(herein referred to as the E1f2)as an example,this paper uses a combination of "level analysis" and"pattern fitting" to conduct in-depth anatomy of the internal architectural pattern of the beach-bars.And summarized the remaining orl distribution patterns controlled by different scale structural elements in the beach-bar sandbodies reservoirs to guide the development of high efficiency water injection in other similar oil fields.Based on the high-resolution sequence stratigraphy study,this paper simultaneously considers factors such as isochronal slices,superposition of sandbodies,and lateral depositional phase changes in the process of stratigraphic comparison,and establishes a fine isochronic stratigraphic framework in the study area.And in the constructed fine isochronal stratigraphic framework,the small layer and single sand layer of Wanglongzhuang-fault-block were compared and divided.On the basis of fine stratigraphic comparisons,taking the moden sedimentary prototype model as a guide,the reservoir architectural of the Wanglongzhuang-fault-block was detailedly anatomized in three levels(composite beach-bars,single bar,and its internal proliferative body).The study shows that the second member of the second section of the Wanglongzhuang Oilfield is a lake-beach-bar-facies deposit,and the vertical single-bar sandbody distribution includes three types:multi-layered,superimposed,and isolated.Each type of sandbodies shows different connectivity.The length and width of a single bar sandbody have a significant positive correlation,with an average aspect ratio of 2.42;The single-bar sandbody develops 1?2 stage hyperplasia inside,and a 0.1?0.8m thick fine-grained muddy interlayer develops between the hyperplasia.And the interlayer is approximately horizontally distributed in the direction of the single-bar sandbody near the lake shoreline,and is inclined at the center of the single bar sandbody at a low angle toward the center of the lake basin.Based on the study of reservoir architectural and dynamic analysis of single well production,the remaining oil distribution models controlled by different scale reservoir elements(composite beach-bars,single bars and their internal accretions)were established.And the reservoir sedinentary geological model and the conceptual model of the reservoir were numerically simulated.The control of the distribution of remaining oil at all levels of structural elements was analyzed.The research directions for remaining oil in the middle and late stages of oilfield development were pointed out.